Turbo-charger shaft brake



A ril 20, 1965 R. A. BOZZOLA 3,179,210

TURBO-CHARGER SHAFT BRAKE Original Filed March 1, 1962 2 Sheets-Sheet 1I INVENTOR.

+ Riccardo A. Bozzola BY flaw/4 3M #MM AHarneys April 20, 1965 R. A.BOZZOLA 3,179,210

' TURBO-CHARGER SHAFT BRAKE Original Filed March 1, 1962 2 Sheets-Sheet2 INVENTOR. Y Riccardo A. Bozzola KZZMMSMEMM United States PatentOfitice 31 l 9 ,2 id Patented Apr. 20, l 965 3 fllairns. (til. Mid-170)This invention relates generally to devices for the protection ofturbocharger bearings when a turbocharged internal combustion engine isstarted, and more particularly relates to a brake device for preventingrotation of a tubocharger shaft until normal lubricating oil pressurehas appeared at the turbocharger shaft bearings.

When a tubocharged internal combustion engine is started cold, anappreciable time interval will normally occur between engine startingand the appearance of lubricating oil under the desired pressure at theturbocharger bearings. If, during this time interval, load is applied tothe engine, because of the increase in engine exhaust gas temperatureand the increased exhaust gas flow, the turbocharger rotor willaccelerate to high speed before satisfactory lubrication is establishedat the turbocharger shaft bearings. This lag in the build-up oflubricating oil ressure can result in serious damage to the turbochargershaft bearings, particularly if journal or sleeve bearings are utilized.

The structure of the present invention protects turbocharger bearingsagainst failure from oil lag. This is accomplished by providing abraking element which is biased into a position preventing rotation ofthe shaft but which is automatically released to permit rotation of theshaft when normal oil pressure appears at the turbocharger bearings.

The primary object of the present invention is to provide an apparatusfor preventing rotation of a turbocharger shaft until lubricating oil isavailable under proper pressure at the shaft bearings.

A further object of the present invention is to provide an apparatus ofthe type referred to which will stop rotation of the turbocharger shaftshould lubricating oil pressure to the shaft bearings fail.

A further object of the present invention is to provide an apparatus ofthe type referred to in which spring biased motion of an oil pressureresponsive piston is transferred to a brake shoe moving in a directionnormal to the turbocharger shaft axis to prevent rotation of the shaft,release of the braking action occurring upon response of the piston to apredetermined oil pressure.

These and other objects will become apparent as the description proceedswith reference to the accompanying drawings in which:

FIG. 1 is an end view of a device embodying the present invention.

FIG. 2 is a sectional view taken generally along the lines 7-7 of FIG.1.

FIG. 3 is a bottom plan view of the structure of FIG. 2 but withportions removed to clarify the interior construction.

Fl 4 is an end view of a portion of the structure shown in FIG. 2.

As is well known in the art, the conventional turbocharger comprisesessentially a turbine and a compressor with the turbine and compressorrotors mounted on a unitary shaft which is hereinafter referred to asthe turbocharger shaft. The turbine is driven by exhaust gases from theengine utilizing the turbocharger and functions to drive theturbocharger compressor which charges the engine cylinders with highpressure air. In the oper ation of a turbocharged engine theturbocharger shaft operates at relatively high speeds and lubrication ofthe turbocharger shaft bearings is quite important. In describing thestructure of the present invention the portions of the turbochargerturbine and compressor are shown only fragmentarily and it will beunderstood that the turbocharger shaft referred to in the description isdriven by the turbine rotor and drives the compressor rotor.

Referring to the drawings, the structure includes a housing indicatedgenerally at 4-1 in FIG. 1 having a flanged base portion 42 which ismounted by means of screws 45 upon bosses 44 welded to the bearinghousing casting to of the turbocharger. It will beunderstood that thebosses could, of course, be integral with the housing and securing meansother than screws 43- might be utilized. The housing 41 further includesa cylindrical portion 4-6 having a central bore 47. As may best be seenin FIGS. 2 and 3 the cylindrical portion is provided with a circularoutwardly flanged portion 48. The flanged portion 48 is closed by a cap49 which, on its inner surface, seats a resilient means in the form of acompression spring 51 and is provided with a drain aperture St). Theupper end, as viewed in PEG. 2, of the compression spring seats againsta piston 52 which is slidable within the flanged portion 48. The outerend face of the piston 52 provides a movable wall 53 for the bore 47.

Referring now particularly to FIGS. 2 and 3 (and in Fl'G. 3 the cap 39,spring 51 and piston 52 are omitted to prevent obscuring of the parts tobe described) the linkage and braking mechanism will now be described.The brake shoe assembly includes a brake shoe proper 54 which extendsfrom a block 56 slidable within the bore 47. The block 56 fits closelyWithin the bore 47 but has flattened, diametrically opposite sidessimilar to a block 66, to be subsequently described, shown in detail inFIG. 4. As may best be seen in FIG. 3 the shoe, at its end, isconfigurated to grip the turbocharger shaft 57 when force is applied tothe shoe producing a tangential frictional force on the shaft resistingits rotation. Since the fiattened sides of block 56 leave a spacebetween the block and the bore wall, lubricating fluid adjacent theshaft 57 may flow inwardly into the bore 47 as indicated by arrows inFIG. 2.

A toggle linkage is disposed within the bore 47 and includes linkmembers 58 and link members 59. The adjacent ends of the two pairs oflinks are pivotally joined by means of a pin 61 and a spacer 62. Theopposite ends of the links 58 are pivotally joined by means of a pin 63to the block 56. The corresponding ends of the links 5% are pivotallyjoined, by means of a pin 64, to a stationary block 66 held fixed withinthe bore by means of the set screw 65. Supported within opposed slots 67and 68 in the blocks 56 and 6e, respectively is a resilient leaf spring69. The slots 67 and 68 retain the leaf spring but are formed so as toprovide freedom of movement for the tips of the spring blade 69 and topermit a slight axial sliding movement of the leaf spring within theslots. The central portion of the leaf spring 59 engages the spacer s2and lightly biases the pivotal junction of the links 58 and 5f away fromthe axial center line of the bore 47 and urges the spacer 62 intoengagement with the movable wall 53. It will be understood that theforce exerted by the spring 69 is 7 far less than the force exerted bythe spring 51 and serves merely to cause the spacer 62 to follow themovements of the movable wall 53 provided by the piston 52.

In operation, prior to the starting of the turbocharged engine the shaft5'7 will, of course, be stationary and the force exerted by the spring51 will, through the toggle linkage drive the shoe 54 into frictionalengagement with the turbocharger shaft. Upon starting of the engine, and

before the lubricating fluid reaches the desired pressure, the spring 51will maintain the shoe 54 against the shaft 57 providing a frictionalforce resisting rotation of the shaft. As the lubricating fiuid pressurewithin the bore 47 builds up to the predetermined value so as toovercome the force exerted by the spring 51 the movable wall 53 will bedisplaced downwardly as viewed in FIG. 2. The spring 69 will cause thepivotal junction of the links 58 and '9 to follow the downward movementof the Wall 53 thereby moving the brake shoe assembly rightwardly asviewed in FIG. 2 and freeing the shoe from the shaft so that the shaftmay rotate. With the bore or cavity 47 directly connected to thelubricating line of the turbocharger the build-up of pressure within thecavity and at the turbocharger shaft bearings will occur substantiallysimultaneously and the turbocharger rotor and turbocharger shaft willthus be permitted to rotate only after adequate lubricating pressure isestablished at the turbocharger bearings. It will be understood that ifthe angle between the toggle linkage members 53 and 59 and the axis ofthe bore 47 is kept relatively small, the force provided by the brakeshoe 54 on the turbocharger shaft 57 can be much greater, that is,multiplied with respect to the force exerted by the spring 51.

While the housings for the devices of both FIGS. 13 have been describedas mounted on the turbocharger bearing housing casting, it will beunderstood that these housings might be integrally formed with thecasting.

While the invention has been disclosed and described in some detail inthe drawings and foregoing description, they are to be considered asillustrative and not restrictive in character, as other modificationsmay readily suggest themselves to persons skilled in this art and withinthe broad scope of the invention, reference being had to the appendedclaims.

The invention claimed is:

l. A device for preventing rotation of a turbocharger shaft and capableof releasing the shaft for rotation upon the appearance of apredetermined lubricating fluid pressure Within the device comprising: ahousing having a central bore therein, said housing being supportedadjacent the turbocharger shaft with the axis of its central 1 borenormal to the shaft axis, a brake shoe assembly slidable within saidbore with its motion in one direction limited by frictional engagementwith said shaft, a toggle linkage disposed within said bore, saidlinkage comprising a first and second links, said first link having oneend pivotally joined to said brake shoe assembly and its other endpivotally joined to one end of said second link, said second link havingits other end pivotally supported by said housing, said links having alength dimension such that their pivotal junction lies to one side ofthe axis of said bore, a movable wall in said housing adjacent thejunction of said links, resilient means urging said wall into engagementwith said junction to move said link junction toward the bore axis andsaid shoe assembly into frictional engagement with the shaft, furtherresilient means relatively lightly biasing said link junction intoengagement with said movable Wall, and means for introducing lubricatingfluid under pressure into said housing bore, whereby as said fluidattains a predetermined pressure, the force exerted by said firstmentioned resilient means is overcome and said movable wall and linkjunction are moved away from said bore axis to displace said shoeassembly out of engagement with the shaft.

2. A device for preventing rotation of a turbocharger shaft and capableof releasing the shaft for rotation upon the appearance of apredetermined lubricating fiuid pressure within the device comprising: ahousing having a central bore therein, said housing being supportedadjacent the turbocharger shaft with the axis of its central bore normalto the shaft axis, a brake shoe assembly slidable within said bore withits motion in one direction limited by frictional engagement with saidshaft, a toggle linkage disposed within said bore, said linkagecomprising a first and second links, said first link having one endpivotally joined to said brake shoe assembly and its other end pivotallyjoined to one end of said second link, said second link having its otherend pivotally supported by said housing, said links having a lengthdimension such that their pivotal junction lies to one side of the axisof said bore, a movable wall in said housing adjacent the junction ofsaid links, resilient means urging said wall into engagement with saidjunction to move said link junction toward the bore axis and said shoeassembly into frictional engagement with the shaft, and means forintroducing lubricating fluid under pressure into said housing bore,whereby as said fluid attains a predetermined pressure the force exertedby said resilient means is overcome and said movable wall and linkjunction are moved away from said bore axis to displace said shoeassembly out of engagement with the shaft.

3. A device for preventing rotation of a turbocharger shaft and capableof releasing the shaft for rotation upon the appearance of apredetermined lubricating fluid pressure within the device comprising: abrake shoe assembly supported for motion transverse to the shaft axiswith its motion in one direction limited by frictional engagement withsaid shaft, a toggle linkage, said linkage comprising a first and secondlinks, said first link having one end pivotally joined to said brakeshoe assembly and its other end pivotally joined to one end of saidsecond link, said second link having its other end pivotally supported,stationary with relation to said brake shoe assembly, a pressureresponsive member adjacent the junction of said links, resilient meansurging said pressure responsive member into engagement with said linkjunction to move said link junction thereby disposing said shoe assemblyin frictional engagement with the shaft, and means for presentinglubricating fluid under pressure to said pressure responsive member,whereby as said fluid attains a predetermined pressure the force exertedby said resilient means is overcome and said link junction is moved todisplace said shoe assembly out of engagement with the shaft.

References Cited by the Examiner UNITED STATES PATENTS ARTHUR L. LAPOINT, Primary Examiner,

1. A DEVICE FOR PREVENTING ROTATION OF A TURBOCHARGER SHAFT AND CAPABLEOF RELEASING THE SHAFT FOR ROTATION UPON THE APPEARANCE OF APREDETERMINED LUBRICATING FLUID PRESSURE WITHIN THE DEVICE COMPRISING: AHOUSING HAVING A CENTRAL BORE THEREIN, SAID HOUSING BEING SUPPORTEDADJACENT THE TURBOCHARGER SHAFT WITH THE AXIS OF ITS CENTRAL BORE NORMALTO THE SHAFT AXIS, A BRAKE SHOE ASSEMBLY SLIDABLE WITHIN SAID BORE WITHITS MOTION IN ONE DIRECTION LIMITED BY FRICTIONAL ENGAGEMENT WITH SAIDSHAFT, A TOGGLE LINKAGE DISPOSED WITHIN SAID BORE, SAID LINKAGECOMPRISING A FIRST AND SECOND LINKS, SAID FIRST LINK HAVING ONE ENDPIVOTALLY JOINED TO SAID BRAKE SHOE ASSEMBLY AND ITS OTHER END PIVOTALLYJOINED TO ONE END OF SAID SECOND LINK, SAID SECOND LINK HAVING ITS OTHEREND PIVOTALLY SUPPORTED BY SAID HOUSING, SAID LINKS HAVING A LENGTHDIMENSION SUCH THAT THEIR PIVOTAL JUNCTION LIES TO ONE SIDE OF THE AXISOF SAID BORE, A MOVABLE WALL IN SAID HOUSING ADJACENT THE JUNCTION OFSAID LINKS, RESILIENT MEANS URGING SAID WALL INTO ENGAGEMENT WITH SAIDJUNCTION TO MOVE SAID LINK JUNCTION TOWARD THE BORE AXIS AND SAID SHOEASSEMBLY INTO FRICTIONAL ENGAGEMENT WITH THE SHAFT, FURTHER RESILIENTMEANS RELATIVELY LIGHTLY BIASING SAID LINK JUNCTION INTO ENGAGEMENT WITHSAID MOVABLE WALL, AND MEANS FOR INTRODUCING LUBRICATING FLUID UNDERPRESSURE INTO SAID HOUSING BORE, WHEREBY AS SAID FLUID ATTAINS APREDETERMINED PRESSURE, THE FORCE EXERTED BY SAID FIRST MENTIONEDRESILIENT MEANS IS OVERCOME AND SAID MOVABLE WALL AND LINK JUNCTION AREMOVED AWAY FROM SAID BORE AXIS TO DISPLACE SAID SHOE ASSEMBLY OUT OFENGAGEMENT WITH THE SHAFT.